Optical Transport Network (OTN: ITU-T G.709), which employs optical paths and the like suitable for Dense Wavelength Division Multiplexing (DWDM) communication, has been standardized through development of optical technology. In the OTN, error correction according to Forward Error Correction (FEC) is used to secure quality of transmission paths in optical transfer networks.
Moreover, increased transmission capacity requests higher capacity communication at OTN rates such as OTU1 (2.5 [G]), OTU2 (10 [G]), OTU3 (40 [G]) and OTU4 (100 [G]). Accordingly, processing adapted to achieve the higher capacity communication is requested, for example, also in the FEC.